Abstract

Chimeric animals are very useful for analysis of cell lineage, homeostasis in tissue architecture, and cell-cell interactions during both organogenesis and carcinogenesis. However, there is not a generally effective means for marking cells of chimeric mice. We have therefore developed a polyclonal antibody that is useful for this purpose. This antibody specifically recognizes those cells derived from C3H strain mice. The specificity of this antibody was checked by both immunoblotting and immunoadsorption methods. The antigens were immunohistochemically detected in cytoplasm of both epithelial and mesenchymal cells of C3H/HeN strain mouse in many different organs, but not the corresponding cell types from BALB/c or C57BL/10 or several other mouse strains. The validity of these antibodies as markers for C3H cells was further checked by tissue recombination experiments and in mixed cultures of mouse and rat cells. In each case the antibody recognized only the C3H mouse cells. Next, chimeric mice were prepared between strains C3H/HeN and BALB/c, and C3H/HeN and C57BL/10 mice. Chimeras 2-mo old were examined for antigen distribution using the indirect immunofluorescence method. Many tissues in chimeric mice were composed of cells that were both stained and unstained by the anti-C3H specific antigen. The chimeric patterns were classified into four types, A-D. In well-defined structural units such as intestinal crypts, small intestinal villi, kidney convoluted tubules, exocrine gland acini, ovarian follicles, thyroid gland follicles, stomach glands, adrenal cortex, lingual papillae, etc., (A) each unit was composed entirely of either positive or negative cells, or else (B) in some organs each unit was composed of both types of cells. In the uniform tissues without such distinguishable units, such as stratified squamous epithelium, mesenchymal tissue, corpora lutea, pituitary gland, Islets of Langerhans, adrenal medulla etc., (C) the tissue was composed of definite small cell groups made entirely of either positive or negative cells, or else (D) the tissue was composed of both types of cells which were intermingled with one another. These findings strongly suggest that the chimeric patterns demonstrated here reflect the cell proliferative unit in each tissue. This cell marker system has proven useful for analysis of cell lineage and cell renewal systems in many organs of chimeric mice.